Numerous measures have been introduced in the past decades to reduce the emissions of harmful substances originating from motor vehicles. One of these measures involves the use of fuel tank systems, in which a fuel tank is connected to a storage element for the temporary storage of hydrocarbons. The refueling of motor vehicles with hydrocarbon-based fuels is associated with the outgassing of hydrocarbons from the fuel, in conjunction with which the hydrocarbons are not meant to be released into the atmosphere. Increased outgassing of hydrocarbons from the fuel also takes place at high temperatures or when traveling over uneven ground, and it is thus necessary to take effective steps to ensure that these hydrocarbons do not escape into the atmosphere. In the case of hybrid vehicles in particular, in which the internal combustion engine remains completely at a standstill over long distances, the outgassed hydrocarbons must be kept effectively in temporary storage before subsequently being burned for the purpose of restarting the internal combustion engine
Fuel tank systems, which consist of a fuel tank and a storage element for the temporary storage of hydrocarbons, have proven themselves to be suitable for this purpose, wherein the fuel tank and the storage element are interconnected in such a way that the hydrocarbons, which outgas from a fuel that is present in the fuel tank, are stored in the storage element, wherein the storage element is connected to a first line, via which fresh air may be supplied to the storage unit, and the storage element is connected to a second line, which connects the storage element to an intake system of the internal combustion engine and via which the fresh air enriched with hydrocarbons may be supplied from the storage element to the intake system. The supply of the fresh air through the storage element takes place with the help of an electrically driven purge air pump. The storage element may be purged periodically with fresh air in this way, and the stored hydrocarbons are supplied to the intake system of an internal combustion engine, wherein the internal combustion engine is supplied with fresh air via the air filter and the intake line. The hydrocarbons that are outgassed from the fuel tank are thus burned in the internal combustion engine, and the escape of the hydrocarbons into the atmosphere is reliably prevented. A purge air pump, which may be configured as a radial pump, is used according to the prior art to supply the hydrocarbons from the storage element to the intake system. This purge air pump must function reliably at relatively high speeds of rotation, ideally for the entire lifetime of the motor vehicle, which imposes special requirements on the sealing elements between moving parts of the purge air pump.